1. Field
Tools especially sockets for use in socket wrenches for driving and holding screws, nuts and bolts with hex heads or Allen wrench heads. Any difference between screws, nuts and bolts generally is not important to this application. Therefore, this application refers to them as “bolts” except where the distinction may be necessary.
2. General Background and State of the Art
Standard socket wrenches usually have two major parts, a handle, which a user can grip, and a socket, which can attach to the handle. The handles' ratcheting mechanism allows the socket to move freely in one direction while the socket remains fixed to the handle when the handle is rotated in the other direction. A switch changes the wrench between tightening and loosening modes. The handle also has a stud, which is inserted into a drive on the socket. Some socket wrenches drive their sockets from the outside of the socket such that the wrench acts on the outside of the base of sockets.
The open end of the socket accepts bolts' hex heads. The typical socket wrench accepts different size sockets, one size for each different size bolt head. Many sockets have six points to conform to bolts' hex head. “Points” are the pointed corners between the faces although the corners often are filleted. Twelve-point sockets have 12 faces such that a common six-sided hex head can be positioned within the socket in one of 12 orientations, each 30° apart. The application refers to “hex heads,” but the term is intended to cover other unconventional polygonal shapes such as squares, pentagons and octagons.
A common use for socket wrenches is driving and removing machine bolts into threaded holes and removing a nut from a bolt thread, but the wrenches also can drive and remove self-threading screws and bolts and wood screws respectively into non-threaded holes and wood. The application discusses bolts into threaded openings and nuts around threaded bolts with the understanding that self-threading screws and bolts and wood screws are included.
When a user installs a bolt into a threaded opening, he or she puts the head into the socket by aligning the faces of the head with corresponding socket faces. The socket is sized to leave a small amount of space between the socket's inside and the outside of the proper hex bolts' head to allow easy insertion of the bolt into the socket. However, the space that allows easy insertion also can allow the bolt to fall from the socket as the user tries to insert the bolt into a threaded opening, Likewise, when users remove a bolt from a threaded opening, they put the socket over the head. Then they turn the wrench counterclockwise until the bolt is unscrewed from its threaded opening. When the user pulls back of the socket wrench, the bolt often falls out of the socket. This may not occur if the socket or bolt is magnetic and the other part is iron.
The problem with inserting or removing the bolt is more pronounced for vertical or nearly vertical openings because of gravity. In many applications such as vehicles and airplanes, when the bolt falls from the socket, it falls into difficult-to-reach locations. Retrieving the bolt wastes time, but leaving a dropped bolt near moving parts may be unsafe.
Others have proposed solutions to this problem. Most involve mounting flat springs in the socket that are positioned along one or more faces or at the intersections of two faces. Inserting a bolt flexes the springs outward, and the restoring force from the springs holds the bolt head. Hu, U.S. Pat. No. 6,098,504 (2000) is an example as are U.S. Pat. No. 6,170,363 (2001) and U.S. Pat. No. 7,712,747 (2008), both to Hu. The springs remain out of contact with the inside face or groove of the socket until a bolt is inserted into the socket. These devices have the following drawbacks. When the socket applies high torque to the head, the springs may deform, which can cause the head to move relative to the springs. Further, only a small area of the spring contacts the bolt head and the socket when the springs bend from a bolt's force. This small area may be insufficient to prevent the bolt from jumping between faces especially when the springs deform.
Some bolts have a round head and a hex-shaped opening in the head. The hex-shaped opening receives the head of an Allen wrench. In many instances, a person repairing a vehicle or performing another task must switch between driving bolts with a socket wrench and an Allen wrench. This may be cumbersome. Some Allen wrenches can be driven by a ratchet wrench, but it would be advantageous if the same socket could drive the same size hex and Allen bolts.